Telegraph repeater



April 4, 1944. v. R. ToLEN TELEGRAPH REPEATER Filed Sept. 17, 1942 l l IL' l Patented Apr. 4, 1944 UNITED STATES ATENT OFFICEY TELEGRAPHREPEATER Virgil R. Tolen, Tinley Park, Ill., assigner to The WesternUnion Telegraph Company, New York, N. Y., a corporation of New Yorin`Application September 17, 1942, Serial No. 458,611

(Cl. FXS- 58) 7 Claims.

'Ihis invention relates to telegraph systems and has particularreference to telegraph signal repeaters of the half duplex type.

It is customary where a line circuit is operated on a full duplex basisto provide at the terminals of the circuit individual receiving andsending legs. Either or both of these legs may be extended by individualextension lines to a branch station. Independent signaling may beeiected simultaneously over the main line circuit and the receiving andsending legs in accordance with well known principles. It may benecessary to combine the legs in some manner because of some failure ofone of the extension lines or of the apparatus associated therewith inorder to provide temporary receiving and transmitting facilities to abranch station connected to the sending and receiving legs. In such acase both sending and receiving signals may be transmitted over thecombined leg but such operations cannot of necessity be simultaneous.The eiiect upon the main line circuit is that the signaling is on whatis known as a half duplex basis.

It is one of the objects of the instant invention to provide animproved, simple, compact and preferably portable apparatus whereby thesending and receiving legs of a system normally operated on a fullduplex basis may be combined to enable the system to be operated on ahalf duplex basis.

Another object of the invention is to provide a novel half duplextelegraph signal repeater.-

A further object of the invention is to provide a half duplex telegraphsignal repeater in which I novel potential responsive means are employedto prevent signals received from a main line circuit from beingreflected back into that circuit.

Still another object of the invention is to provide, in a half duplextelegraph signal repeater, signal reilection prevention means which arecontrolled by the potentials in the combined receiving and sending legrather than by the signaling currents flowing therein.

rIhese and other objects of the invention are attained in the embodimentchosen for illustration and will become apparent from the followingdescription Which is taken in conjunction with the single gure of theaccompanying drawing.

The main line circuit L which normally is operated on a full duplexbasis is terminated in the conventional duplex bridge i. Signalsreceived over the main line circuit operate a receiving device Zby meansof which a transmitting element 3 is controlled. The transmitter 3 isconnected in the receiving leg which comprises a series circuitincluding a grounded negative battery 4, the sleeve, tip and normalccntacting elements of a jack 5, extension line t, the receiving andtransmitting elements of a combined transmitter-receiver l, andresistance to ground. The combination transmitter-receiver l, which fornormal operation is used for receiving, may be located at a branchstation 9 which also includes a second combination transmitter-receiverll. The combination transmitter-receiver H is normally used for sendingfrom the branch station and is connected in the sending leg whichcomprises a series circuit extending from ground at the branch stationthrough resistance l 2, the transmitting and receiving elements of vthecombination transmitter-receiver Il, extension line I3, the tip, sleeveand normal contacting elements of a jack i 4, a signal receiver I5 andgrounded negative battery 4. The signal receiver l5 controls atransmitting device It by means of which signals are transmitted overthe main line L.

Such an arrangement. is customarily utilized for full duplex operationof a main line telegraph circuitJ and independent signaling may beeiected simultaneously over both the receiving and sending legsextending to the branch office 9. In the event that a circuit failure ofone of the extension linesoccurs, either because of a fault in the lineWire itself or because of the failure of the printing equipment locatedat the branch station, the branch station is deprived of either sendingor receiving facilities depending upon which leg fails. The presentinvention enables such a branch station to be furnished temporarily withboth sending and receiving facilities.

Assume that When a failure of such a character occurs, the normalreceiving leg utilizing extension line 6 is incapacitated. Plugs il andi8, in which are terminated the leg combining facilities in accordancewith the present invention, are inserted respectively in jacks 5 andifi. The blades of a switch IS are placed in engagement with their lowercontacts are shown. Such an arrangement permits the use of the extensionline I3 and the combined transmitter-receiver il at the branch station 9to be used both as a sending and as a receiving leg, but of course suchuses are not simultaneous.

In this case the combined receiving and sending leg extends fromgrounded negative battery 4 through the transmitting device 3, therespective sleeve elements of jack 5 and plug I1, the lower contact andblade 2| of switch I9, the left hand or operating winding of a repeatingrelay 22, the sleeve, tip and normal contacting elements of a monitorjack 23, the respective tip elements of plug I8 and jack I4, extensionline I3, the receiving and transmitting elements of the combinedtransmitter-receiver I|, and resistance I2 to ground. It is seen thatthe transmitting elements of the combined transmitter-receiver II andthe transmitting device 3 thus are connected in series with thereceiving element of the combined transmitter-receiver II and with onewinding of the repeating relay 22. The contacts 24 of the repeatingrelay are connected in a local circuit extending from ground through theblade 25 and lower contact of switch I9, the respective sleeve elementsof the plug I8 and the jack I4, the signal receiving device I5, andgrounded negative battery 4. Consequently, the receiving device I5 iscontrolled by the contacts 24 of the repeating relay 22 to actuate thetransmitter I6 whereby signals are'transmitted over the main line L.

In order to prevent the signals which are received from the main linecircuit L from lbeing retransmitted back over the main line circuit, itis necessary to prevent the contacts 24 of the repeating relay 22 fromrepeating the signals which are applied to its left hand winding :by thetransmitting device 3. For this purpose the repeating relay is providedwith a right hand or locking winding which is connected in series with abattery 26 and the space discharge path of a vacuum tube 21. The controlgrid of the tube 2'1 is connected to a point on the combined sending andreceiving leg circuit which is located between the transmitting device 3and the transmitting element of the combination transmitter-receiver Ilat the branch station 9. The impedances on either side of this point arearranged so that with lboth transmitters in marking or closed positions,the potential of the grid element is suiiiciently negative with respectto the grounded cathode to bias the tube beyond the point of cutoiand tothereby render the tube non-conducting.

Assume that transmission is taking place at the branch station and thesignals are to be repeated into the main line circuit L. As the combinedreceiving and sending leg circuit is opened and closed for thetransmission of spacing and marking signals respectively, the left handor operating winding of the repeating relay 22 is deenergized andenergized. With each opening of the branch station transmitter, groundis disconnected from the combined receiving and sending leg whichinterrupts the ilow of current in this circuit and places the controlgrid of the vacuum tube 27 at the full negative potential of the battery4. The tube is thus biased still furthere beyond the cutoff point and ismaintained non-conducting. Consequently, the right hand or lockingwinding of the repeating relay 22 is not energized and, in response tothe deenergization of the left hand winding, the contacts 24 open torepeat the spacing signal to the receiving device I5 whereby thetransmitter I6 may be controlled to repeat the signal over the main linecircuit L.

When the transmitting device 3 operates in response to a spacing signalreceived from the main line L to open its contacts, the left hand oroperating winding of the repeating relay 22 is again deenergized. Inthis case, however, the opening of the contacts of the transmittingdevice 3 disconnects negative potential from the comiii" bined receivingand sending leg, leaving the control grid of the tube 21 at the groundpotential derived from the branch station 9. With both the grid and thecathode elements of the tube 2T at ground potential, the tube becomesconducting to energize the right hand or locking winding of therepeating relay 22 and to thereby prevent the opening of the contacts24. Thus, it is seen that the spacing signal received from the main linecircuit L is not reflected back into the main line since the receivingdevice I5 is maintained in a marking condition under the control of thecontacts 24 of the repeating relay 22 to control the transmitter I6 in amanner to apply a steady marking signaling condition to the main line L.

In the event that it is desired to temporarily use the extension line 6and the combination transmitter-receiver 1 at station 9 in a combinedsending and receiving leg, the plug I8 is inserted in jack 5 and plug I1is inserted in jack |4. The blades 2| and 25 of switch I9 are moved intoengagement with their upper contacts. It will be seen then that there isestablished a series circuit including grounded negative battery 4, thetransmitting device 3, the respective sleeve elements of jack 5 and plugI8, upper contact and switch blade 2| of the switch I9, the left hand`or operating winding of the relay 22, the monitor` jack 23, therespective tip elements of plug I8 and jack 5, the extension line 6, thecombination transmitter-receiver 1, and resistance 8 to ground. Thecontacts 24 of relay 22 control the local circuit extending from groundthrough the switch blade 25 and its upper contact, the respective sleeveelements of plug I1 and jack I4, the receiving device I5 and groimdrednegative battery 4.

The operation of the system is the same as that previously described.Signals transmitted by the transmitting element of the combinationtransmitter-receiver I are repeated by relay 22 to actuate the receivingdevice Irwhereby the transmitter I6 is controlled to further repeat thesignals to the main line L. Signals sent by the transmitting device 3are received by the receiving element of the combinationtransmitter-receiver l and are prevented, by the operations of thevacuum tube 21, from actuating the repeating relay 22 whereby thereceiving device I5 is not operated to control the retransmission oisuch signals to the main line L. Y

When the system is arranged for normal ful duplex operation, a monitor'printer 28 comprising transmitting and receiving elements may beconnected in either the sendingy or receiving leg by the insertion of aplug 29 into lack `I4 or 5, respectively.

The receiving and sending legs are normally connected through contactsof jacks 5 and I4, respectively, and include the respective resistances3| and 32. Such resistances are proportioned to balance the resistanceof either the monitor printer 28 or the leg combining apparatusdepending upon which is plugged into the jacks so that at all times thecurrent flowing in the receiving and sending legs is substantially thesame. The monitor jack 23, yinto which the plug 29 is inserted formonitoring purposes when the apparatus is arranged to combine thereceiving and sending legs, is also provided with a similar resistance33 for substantially the same purpose.

The nature of the invention may be ascertained from the foregoingdescription of an illustrative embodiment thereof, it being understoodthat other modifications incorporating the same inventive idea may bemade within the scope of what is claimed without departing from thespirit of the invention.

What is claimed is:

l. In a telegraph system, a line circuit, a repeating device to controlsignal transmission to said line circuit, means for relaying signalsreceived from said line circuit, a signal transmitter, means forconnecting said signal relaying means and said transmitter to similarlyiniiuence said repeating device, and potential actuated means associatedwith said signal relaying means and said transmitter and operable onlyin response to operation of said signal relaying means to render saidrepeating device responsive to said transmitter and unresponsive to saidsignal relaying means whereby signals received from said line circuitare not retransmitted to said line circuit.

2. In a half duplex telegraph signal repeater, a repeating deviceoperable to control signal transmission to a line circuit and having anoperating circuit and a locking circuit, two transmitting devices, onecontrolled by signal'reception from said line circuit and both connectedto similarly condition said operating circuit, and means actuated bypotentials in said operating circuit resulting from operation of saidline signal controlled transmitter to operatively condition said lockingi circuit whereby said repeating device is rendered inoperative.

3. In a half duplex telegraph signal repeater, a first transmittercontrolled by received line signais, a local receiving device forcooperation with said iirst transmitter, a local transmitter, a secondreceiving device for cooperation with said local transmitter to transmitline signals, means for connecting said transmitters and said receivingdevices in a local circuit, means responsive to potentials in a part ofsaid local circuit between said transmitters, and means controlled bysaid voltage responsive means for preventing the repetition by saidsecond receiving device of signals originating at said rst transmitter.

4. In a half duplex telegraph signal repeater, a combined sending andreceiving leg comprising the series connection of a iirst transmitterresponsive to signals received from a main line circuit, a localtransmitter, a local receiving device responsive to either of saidtransmitters, a second receiving device to control the transmission ofsignals over said main line, and means including a potential responsivedevice connected to said combined sending and receiving leg and operableby said iirst transmitter but not by said local transmitter forrendering said second receiving device unresponsive to said rsttransmitter.

5. In a half duplex telegraph signal repeater, a combined sending andreceiving leg comprising a series connection of a grounded source ofdirect current, a first transmitter responsive to signals received froma main line, a repeating device to control the transmission of signalsover said main line, a local receiving device and a local transmitter,said local receiving device being responsive to both of saidtransmitters, and voltage controlled means connected to said combinedsending and receiving leg at a point between said transmitters andoperable in response to operations of said rst transmitter to preventsaid repeating device from relaying signals originating at said rsttransmitter.

6. In a half duplex telegraph signal repeater, a local circuitcomprising two transmitters, a receiver and a repeating relay connectedin series and having one terminal thereof connected to a grounded sourceof direct current and the other terminal to ground, and a vacuum tubehaving its control element connected to said local circuit at a pointbetween said transmitters and its output circuit connected in serieswith a locking winding of said repeating device whereby said repeatingdevice responds to one of said transmitters but not the other.

7. In a telegraph system, a substation having a combinationtransmitter-receiver normally used for sending and another combinationtransmitter-receiver normally used for receiving, a central stationhaving a transmitter and a receiver, a sending line normally connectingsaid sending transmitter-receiver with said receiver, a receiving linenormally connecting said receiving transmitter-receiver with saidtransmitter, a relay at said central station having an operating coil, alocking coil and contacts controlled by either of said coils, means forconnecting said operating coil in circuit with one of said lines andWith said transmitter, means for connecting said receiver to respond tothe control of said contacts, and means subject to line potentials andoperable in response to operations of said transmitter but not inresponse to operations of the transmitter of the combinationtransmitterreceiver associated with the line having in circuit saidoperating coil to energize said looking coil whereby said relay isprevented from repeating the signals originating at said transmitter.VIRGIL R. TOLEN.

